| Message ID | ac35a419e395d355d86f3b44ce219dc63864db00.1600114548.git.thomas.lendacky@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | SEV-ES hypervisor support | expand |
On 9/14/20 4:39 PM, Sean Christopherson wrote: > On Mon, Sep 14, 2020 at 03:15:40PM -0500, Tom Lendacky wrote: >> From: Tom Lendacky <thomas.lendacky@amd.com> >> >> The guest FPU is automatically restored on VMRUN and saved on VMEXIT by >> the hardware, so there is no reason to do this in KVM. > > I assume hardware has its own buffer? If so, a better approach would be to > not allocate arch.guest_fpu in the first place, and then rework KVM to key > off !guest_fpu. Yup, let me look into that. Thanks, Tom > >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> >> --- >> arch/x86/kvm/svm/svm.c | 8 ++++++-- >> arch/x86/kvm/x86.c | 18 ++++++++++++++---- >> 2 files changed, 20 insertions(+), 6 deletions(-) >> >> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c >> index b35c2de1130c..48699c41b62a 100644 >> --- a/arch/x86/kvm/svm/svm.c >> +++ b/arch/x86/kvm/svm/svm.c >> @@ -3682,7 +3682,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) >> svm_set_dr6(svm, DR6_FIXED_1 | DR6_RTM); >> >> clgi(); >> - kvm_load_guest_xsave_state(vcpu); >> + >> + if (!sev_es_guest(svm->vcpu.kvm)) >> + kvm_load_guest_xsave_state(vcpu); >> >> if (lapic_in_kernel(vcpu) && >> vcpu->arch.apic->lapic_timer.timer_advance_ns) >> @@ -3728,7 +3730,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) >> if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI)) >> kvm_before_interrupt(&svm->vcpu); >> >> - kvm_load_host_xsave_state(vcpu); >> + if (!sev_es_guest(svm->vcpu.kvm)) >> + kvm_load_host_xsave_state(vcpu); >> + >> stgi(); >> >> /* Any pending NMI will happen here */ >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 76efe70cd635..a53e24c1c5d1 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -8896,9 +8896,14 @@ static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) >> >> kvm_save_current_fpu(vcpu->arch.user_fpu); >> >> - /* PKRU is separately restored in kvm_x86_ops.run. */ >> - __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state, >> - ~XFEATURE_MASK_PKRU); >> + /* >> + * An encrypted save area means that the guest state can't be >> + * set by the hypervisor, so skip trying to set it. >> + */ >> + if (!vcpu->arch.vmsa_encrypted) >> + /* PKRU is separately restored in kvm_x86_ops.run. */ >> + __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state, >> + ~XFEATURE_MASK_PKRU); >> >> fpregs_mark_activate(); >> fpregs_unlock(); >> @@ -8911,7 +8916,12 @@ static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) >> { >> fpregs_lock(); >> >> - kvm_save_current_fpu(vcpu->arch.guest_fpu); >> + /* >> + * An encrypted save area means that the guest state can't be >> + * read/saved by the hypervisor, so skip trying to save it. >> + */ >> + if (!vcpu->arch.vmsa_encrypted) >> + kvm_save_current_fpu(vcpu->arch.guest_fpu); >> >> copy_kernel_to_fpregs(&vcpu->arch.user_fpu->state); >> >> -- >> 2.28.0 >>
On Tue, Sep 15, 2020 at 09:25:18AM -0500, Tom Lendacky wrote: > On 9/14/20 4:39 PM, Sean Christopherson wrote: > > On Mon, Sep 14, 2020 at 03:15:40PM -0500, Tom Lendacky wrote: > >> From: Tom Lendacky <thomas.lendacky@amd.com> > >> > >> The guest FPU is automatically restored on VMRUN and saved on VMEXIT by > >> the hardware, so there is no reason to do this in KVM. > > > > I assume hardware has its own buffer? If so, a better approach would be to > > not allocate arch.guest_fpu in the first place, and then rework KVM to key > > off !guest_fpu. > > Yup, let me look into that. Heh, it's on our todo list as well :-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index b35c2de1130c..48699c41b62a 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3682,7 +3682,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) svm_set_dr6(svm, DR6_FIXED_1 | DR6_RTM); clgi(); - kvm_load_guest_xsave_state(vcpu); + + if (!sev_es_guest(svm->vcpu.kvm)) + kvm_load_guest_xsave_state(vcpu); if (lapic_in_kernel(vcpu) && vcpu->arch.apic->lapic_timer.timer_advance_ns) @@ -3728,7 +3730,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu) if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI)) kvm_before_interrupt(&svm->vcpu); - kvm_load_host_xsave_state(vcpu); + if (!sev_es_guest(svm->vcpu.kvm)) + kvm_load_host_xsave_state(vcpu); + stgi(); /* Any pending NMI will happen here */ diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 76efe70cd635..a53e24c1c5d1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8896,9 +8896,14 @@ static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu) kvm_save_current_fpu(vcpu->arch.user_fpu); - /* PKRU is separately restored in kvm_x86_ops.run. */ - __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state, - ~XFEATURE_MASK_PKRU); + /* + * An encrypted save area means that the guest state can't be + * set by the hypervisor, so skip trying to set it. + */ + if (!vcpu->arch.vmsa_encrypted) + /* PKRU is separately restored in kvm_x86_ops.run. */ + __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu->state, + ~XFEATURE_MASK_PKRU); fpregs_mark_activate(); fpregs_unlock(); @@ -8911,7 +8916,12 @@ static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) { fpregs_lock(); - kvm_save_current_fpu(vcpu->arch.guest_fpu); + /* + * An encrypted save area means that the guest state can't be + * read/saved by the hypervisor, so skip trying to save it. + */ + if (!vcpu->arch.vmsa_encrypted) + kvm_save_current_fpu(vcpu->arch.guest_fpu); copy_kernel_to_fpregs(&vcpu->arch.user_fpu->state);